The present invention relates to latches and latching methods, and more particularly to devices and methods for controlling and switching a latch between latched and unlatched states.
Conventional latches are used to restrain the movement of one member or element with respect to another. For example, conventional door latches restrain the movement of a door with respect to a surrounding door frame. The function of such latches is to hold the door secure within the door frame until the latch is released and the door is free to open. Existing latches typically have mechanical connections linking the latch to actuation elements such as handles which can be actuated by a user to release the latch. Movement of the actuation elements is transferred through the mechanical connections and (if not locked) can cause the latch to release. The mechanical connections can be one or more rods, cables, or other suitable elements or devices. Although the following discussion is with reference to door latches (e.g., especially for vehicle doors) for purposes of example and discussion only, the background information and the disclosure of the present invention provided applies equally to a wide variety of latches used in other applications.
Most current vehicle door latches contain a restraint mechanism for preventing the release of the latch without proper authorization. When in a locked state, the restraint mechanism blocks or impedes the mechanical connection between a user-operable handle (or other door opening device) and a latch release mechanism, thereby locking the door. Many conventional door latches also have two or more lock states, such as unlocked, locked, child locked, and dead locked states. Inputs to the latch for controlling the lock states of the latch can be mechanical, electrical, or parallel mechanical and electrical inputs. For example, by the turn of a user""s key, a cylinder lock can mechanically move the restraint mechanism, thereby unlocking the latch. As another example, the restraint mechanism can be controlled by one or more electrical power actuators. These actuators, sometimes called xe2x80x9cpower locksxe2x80x9d can use electrical motors or solenoids as the force generator to change between locked and unlocked states.
Regardless of the mechanism employed to change the locked state of a latch assembly (to disable or enable a mechanical or electrical input to the latch assembly), a problem common to the vast majority of conventional door latches relates to the inability of such door latches to properly respond to multiple inputs at a given time. A well-recognized example of this problem is the inability of most conventional door latches to properly respond to a user unlocking the door latch while the door handle is partially or fully actuated. While this problem can exist for door latches that are not powered, it is particularly problematic in powered latches. For example, a user of a keyless entry system can push a button on a key fob, enter an access code on a door keypad, or otherwise transmit a signal (by wire or wirelessly) to a controller in the vehicle that in turn sends a signal to power unlock a handle input to the latch. In conventional power latches, an amount of time is required for this process to take place. During this time, a user may attempt to unlatch the latch by actuating the handle input. Because the latch has not yet been unlocked, such actuation does nothingxe2x80x94even though the latch is attempting to power itself to its unlocked state while the handle input is in a partially or fully actuated position. The user must release and re-actuate the handle to unlatch the latch. In other words, to unlatch a conventional latch, actuation of the handle input must occur after the handle input has been placed in its unlocked state. Partial or full actuation of the handle input before this time will not unlatch the latch and will require the user to release and re-actuate the handle input.
This shortcoming of conventional door latches exists for powered and fully manual door latches alike. In addition to requiring the user to re-actuate an input to unlatch the unlocked latch, this problem can even prevent the latch from changing between its locked and unlocked states. In such a case, the user is required to unlock the latch assembly again (re-transmit a signal to the latch assembly or manually unlock the latch assembly again as described above) after the handle input has been released. Any of the results just described represent an annoying attribute of conventional latch assembly designs. In this and other examples, a conventional latch assembly is unable to respond to actuation of more than one input at a time, or is only responsive to one of two inputs actuated simultaneously or closely in time.
It is possible to add structure and elements to conventional door latch designs in order to address the above-noted problems. However, such additional structure and elements are likely to increase latch complexity. Increased latch complexity also increases assembly and repair cost. Accordingly, the reasonable door latch design alternatives available to address the above-noted problems of conventional door latches are significantly limited.
Problems of latch weight and size are related to the problem of latch complexity. The inclusion of more elements and more complex mechanisms within the latch generally undesirably increases the size and weight of the latch. In virtually all vehicle applications, weight and size of any component is a concern. Therefore, many latch designs employing additional structure and elements to address the above-noted problems do so at an unacceptable cost of increased latch weight and size.
In light of the problems and limitations of the prior art described above, a need exists for a latch assembly which is able to properly respond to an unlocking/locking input and to a latching/unlatching input received simultaneously or closely in time, does so with minimal to no additional latch assembly elements and structure, does not negatively impact latch complexity and cost, and can be achieved by relatively simple modification of many existing latch assembly designs. Each preferred embodiment of the present invention achieves one or more of these results.
The latch assembly of the present invention is capable of properly responding to unlatching and unlocking inputs received at the same time or closely in time. In other words, when an unlatching input is received before or while an associated locking mechanism is placed in its unlocked state, the latch assembly properly responds by unlatching the latch upon movement of the locking mechanism to the unlocked state. In one preferred application involving a car door latch capable of being unlocked via a remote keyless entry system, the user can partially or fully actuate the door handle prior to unlocking the door or while the door is being unlocked (e.g., while the keyless entry system is still processing the request to unlock the latch assembly, during movement of the locking mechanism to its unlocked state, and the like). The latch assembly responds by unlatching the latch when the latch assembly is finally unlocked, and does so without requiring the user to release and re-actuate the door handle.
Some preferred embodiments of the present invention include a pawl releasably engagable with a ratchet latching the door in place, a user-manipulatable handle, a cam movable between an unlocked position (in which actuation of the cam by the handle generates sufficient pawl movement to release the ratchet) and a locked position (in which actuation of the cam by the handle does not generate sufficient pawl movement to release the ratchet), and a lock coupled to the cam for moving the cam between its unlocked and locked positions. In some highly preferred embodiments of the present invention, the lock is jointed to provide compound movement of the cam between its unlocked and locked positions.
The cam preferably has at least one cam surface that, when the cam is moved by the lock toward its unlocked position, cams against one or more surfaces of the pawl, the handle, or both the pawl and the handle if the handle is already actuated (fully, partially to any extent and/or partially to at least some minimum extent). To provide for smoother camming motion, cam surfaces of the cam, pawl, and handle are preferably brought together at a relatively shallow angle. Also for this same purpose, these surfaces are preferably beveled, blunted, bowed, chamfered, rounded, sloped, or otherwise shaped to present at least a portion of each surface at a relatively shallow angle with respect to the opposing cam surface. Preferably, if the handle has not yet been actuated, the cam can be moved between its unlocked and locked positions without camming action against the pawl or handle or at least with minimal camming action.
In some highly preferred embodiments of the present invention, the cam is movable within an aperture in the pawl, an aperture in the handle, or apertures in both the pawl and handle. For example, the cam can be movable by the lock through an aperture in the handle into and out of a position adjacent to the pawl in which actuation of the handle forces the cam against the pawl and thereby causes the pawl to move toward its unlatched position. The lock in this case can move the cam into camming contact with the pawl (to move the pawl toward its unlatched position) even after partial or full actuation of the handle. The handle aperture in this example can function to guide the cam in its motion between its unlocked and locked positions and can also provide a surface to press or cam against the cam which in turn cams against the pawl. As another example, the cam can be movable within apertures in the handle and the pawl. When the handle is partially or fully actuated, the apertures become misaligned. Upon movement of the cam into and/or through the apertures, the cam cams against a surface of the pawl aperture (and preferably also against a surface of the handle aperture) to re-align the pawl and handle apertures and to thereby move the pawl toward its unlatched position.
In various alternative embodiments, the cam can be movable into and out of pawl and/or handle apertures by actuation of the lock. As used herein and in the appended claims, the term xe2x80x9caperturexe2x80x9d includes any type of hole, cavity, orifice, recess, groove, slot, or other opening. The xe2x80x9caperturexe2x80x9d can be closed to the sides of the element in which it is defined or can be open to such sides. For example, the aperture can be a cavity located within the pawl or handle or can be a notch or recess in a side of the pawl or handle. The aperture may or may not extend fully through the element in which it is defined.
In still other alternative embodiments, the lock is rotatably connected to the pawl, whereby the cam instead cams against a cam surface of the handle if the handle has already been partially or fully actuated. This camming motion transmits rotational force to the pawl to move the pawl toward its unlatched position.
In most highly preferred embodiments of the present invention, movement of the cam (by actuation of the lock) to an unlocked position while the handle is in an actuated position as described above brings the cam into camming engagement with the pawl, the handle, or with both the pawl and the handle. This camming engagement transmits motive force to the pawl to move the pawl toward its unlatched position. The term xe2x80x9cmotive forcexe2x80x9d as used herein and in the appended claims means that force is transferred that is sufficient to generate motion of an element.
Because most conventional latch assemblies include a pawl, a handle, and a lock of some type, the present invention typically does not involve any significant addition of elements or latch assembly structure. Also, existing latch assembly designs can often be easily modified to operate in accordance with the present invention. Therefore, the present invention has little to no negative impact upon latch weight, complexity, and assembly and repair cost, and provides significant advantages over conventional latch assembly designs.
More information and a better understanding of the present invention can be achieved by reference to the following drawings and detailed description.